JP6515812B2 - Phenolic resin composition for friction material, friction material and brake - Google Patents

Description

  The present invention relates to a phenolic resin composition for friction material, a friction material and a brake.

  Phenolic resin compositions are materials having excellent heat resistance and adhesiveness with inorganic fillers, and are widely used as binders for friction materials such as brakes. As a specific example of the phenol resin composition generally used as a binder for friction materials mentioned above, powdery thermosetting phenol resin obtained by pulverizing and mixing random novolak type phenol resin and hexamethylenetetramine A composition etc. are mentioned.

  In a typical production process of a friction material such as a brake using a phenolic resin composition, a fibrous inorganic material such as glass fiber, aramid fiber, metal fiber, etc., as opposed to a thermosetting phenolic resin composition used as a binder The resin mixture obtained by mixing the filler base material and the powdered inorganic filler such as calcium carbonate and barium sulfate is heat-pressed in a hot-pressing device to produce a molded body.

  And the binder for friction materials mentioned above is conventionally required to have characteristics such as high strength, heat resistance, abrasion resistance, high friction coefficient, low noise, low hygroscopicity, high vibration absorbability and the like. In particular, in recent years, in order to improve the productivity of the friction material, it is required to improve the curability of the phenolic resin composition for friction material. In order to satisfy such a required level, various studies have been made on phenolic resin compositions for friction materials.

  For example, in Patent Document 1, an acid substance is used to accelerate the decomposition rate of hexamethylenetetramine, which uses a high ortho novolac type phenol resin as a novolac type phenol resin in order to improve the curability of a phenol resin composition for friction material. In addition, there is disclosed a technique such as adding a high ortho novolac type phenolic resin and hexamethylenetetramine by melt-kneading.

JP 2005-272548 A

  The prior art described in Patent Document 1 and the like can shorten the gelation time, and therefore, some effect can be expected in that the time required for the pressing process can be shortened. However, the inventors of the present invention have found that there is room for improvement in the prior art described above in that sufficient mechanical properties can not be obtained because the strength and hardness of the molded body decrease.

  Therefore, the present invention is a phenol for friction material that can obtain a friction material having excellent heat resistance without reducing various properties such as mechanical properties by reaching a high degree of curing even if the curing time is shortened. Provided is a resin composition.

According to the invention, a high ortho novolac phenolic resin,
Novolak-type resorcinol resin obtained by the reaction of resorcinol with formaldehyde ;
With hexamethylenetetramine,
Only including,
The phenolic resin composition for friction materials , wherein the ortho / para bond ratio of the high ortho novolac type phenolic resin is 2 or more and 7 or less is provided.

Furthermore, according to the invention, a fiber substrate,
With fillers
A binder,
A friction material containing
A friction material is provided, wherein the binder comprises the above-mentioned phenolic resin composition for friction material.

  Furthermore, according to the present invention, a brake formed using the above-mentioned friction material is provided.

  According to the present invention, it is possible to obtain a friction material having excellent heat resistance without reducing various properties such as mechanical properties by reaching a high degree of curing even if the curing time is shortened. A resin composition can be provided.

<Phenolic resin composition for friction material>
The phenol resin composition for a friction material according to the present embodiment contains a high ortho novolac type phenol resin, a novolac type resorcinol resin, and hexamethylenetetramine. Thereby, even if hardening time is shortened, it can be considered as a phenol resin composition for friction materials which can realize a high degree of hardening.

  The phenolic resin composition for a friction material according to the present embodiment is assumed to be used as a raw material for producing a friction material by using three components of a high ortho novolac type phenolic resin, a novolac type resorcinol resin and hexamethylenetetramine in combination. It is According to the phenolic resin composition for a friction material according to the present embodiment, the curability of the resin composition can be obtained even when molding at a high temperature is performed at the time of producing a friction material by using the three components described above in combination. The balance of the degassing properties can be maintained in a good state. For this reason, by using the phenolic resin composition for a friction material according to the present embodiment, it becomes possible to mold the friction material in a short time. This can significantly reduce the manufacturing cost of the friction material.

  The phenolic resin composition for a friction material according to the present embodiment preferably contains, as a resin component, a resin mixture of a high ortho novolac type phenolic resin and a novolac type resorcinol resin. By so doing, when the curing time is shortened, the degree of curing can be significantly improved.

  The content of the novolac-type resorcinol resin is preferably 1 part by mass or more and 100 parts by mass or less, and more preferably 3 parts by mass or more and 85 parts by mass or less with respect to 100 parts by mass of the high ortho novolac phenol resin. , Most preferably, it is 4 parts by mass or more and 50 parts by mass or less. By setting the content of the novolac type resorcinol resin to the above lower limit value or more, the degree of curing can be more reliably increased when the curing time is shortened. Further, by setting the content of the novolac type resorcin resin to the upper limit value or less, it is possible to prevent the deterioration of the moldability.

  The high ortho novolac type phenolic resin according to the present embodiment is obtained by reacting phenols and aldehydes in the presence of an acidic catalyst. In the above-mentioned high ortho novolac type phenol resin, the ratio (ortho / para bond ratio) of the bonding position of the methylene group or substituted methylene group derived from aldehydes to the phenolic hydroxyl group of phenols is preferably 1 or more and 9 or less From the viewpoint of ease of production, it is more preferably 2 or more and 7 or less, and most preferably 2.5 or more and 7 or less. By doing this, it is possible to obtain a resin composition having a faster curing rate as compared to the conventional random novolac phenolic resin. So, the molding time at the time of friction material manufacture using the phenol resin composition for friction materials concerning this embodiment can be shortened. In addition, in order to synthesize a high ortho novolac type phenol resin having an ortho / para bond ratio within the above numerical range, it is important to control factors such as the reaction temperature, the reaction time and the like. However, as the high ortho novolac type phenol resin, a commercial product prepared to have the above-mentioned ortho / para bonding ratio may be used.

Here, ortho / para bond ratio of high-ortho novolak type phenolic resin, when measured by infrared absorption spectroscopy, wavenumber 760 cm ^-1, and it can be calculated from the absorbance at the wave number 820 cm ^-1. Specifically, the ortho / para bond ratio can be calculated by the following equation. Incidentally, D760 in the following formula indicates the absorbance at 760 cm ^-1, D820 shows the absorbance of the 820 cm ^-1.
Formula: ortho / para coupling ratio = D760 / (1.44 × D820)

  Specific examples of phenols used for the synthesis of high ortho novolac type phenol resin include phenol, orthocresol, metacresol, paracresol, xylenol, parabutylphenol, paraoctylphenol, paraphenylphenol, bisphenol A, bisphenol F, There may be mentioned phenols such as resorcin. One of these may be used alone, or two or more of these may be used in combination. Above all, it is preferable to use phenol or cresol from the viewpoint of production cost and moldability.

  Specific examples of the aldehydes used for the synthesis of the high ortho novolac type phenol resin include aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde, butyraldehyde, acrolein, etc., or a mixture thereof, a substance serving as a generation source of the aldehydes described above And solutions of the above-mentioned aldehydes. Among them, it is preferable to use formaldehyde from the viewpoint of production cost and moldability.

  Examples of the high ortho novolac type phenol resin and novolac type resorcinol resin include various forms such as liquid, solid, powder and the like, and among them, solid form is preferable from the viewpoint of handling property.

  The high ortho novolac type phenol resin is controlled so that the reaction molar ratio (F / P) of aldehydes (F) to phenols (P) is in the range of 0.5 to 0.9. Is preferred. This makes it possible to synthesize a high ortho resin having a suitable molecular weight without gelation of the resin during the reaction. The quantity of unreacted phenols contained in the high ortho resin obtained as a reaction molar ratio is more than the said lower limit can be reduced. In addition, when the reaction molar ratio is equal to or less than the above upper limit value, it is possible to suppress the gelation of the resin depending on the reaction conditions.

  The weight average molecular weight of the high ortho novolac type phenol resin is preferably 1000 or more, more preferably 2000 or more. By this, it is possible to improve the glass transition temperature when the curing time is shortened. The upper limit value of the weight average molecular weight of the high ortho novolac phenol resin is preferably 8,000 or less from the viewpoint of moldability.

  Examples of the acidic catalyst used for the reaction of the high ortho novolac phenol resin include compounds containing divalent metal ions when dissolved in phenol. Specific examples thereof include zinc acetate and lead naphthenate.

  Next, the novolak-type resorcinol resin according to the present embodiment is obtained, for example, by reacting resorcins with aldehydes in the presence of an acidic catalyst and then removing water by a dehydration step.

  Specific examples of the above-mentioned resorcins used for the synthesis of novolac-type resorcin resins include resorcins, methylresorcins such as 2-methylresorcin, 5-methylresorcin, 2,5-dimethylresorcin, 4-ethylresorcin, 4-chloro Resorcin, 2-nitroresorcin, 4-bromoresorcin, 4-n-hexylresorcin and the like. These may be used alone or in combination of two or more. Among them, at least one selected from the group consisting of resorcin and methyl resorcins is preferable from the viewpoint of production cost and moldability.

  Specific examples of the above-mentioned aldehydes used for the synthesis of novolac type resorcin resin include aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde, butyraldehyde and acrolein, or a mixture thereof, substances which are the sources of the above-mentioned aldehydes and And solutions of the above-mentioned aldehydes. Among them, it is preferable to use formaldehyde from the viewpoint of production cost and moldability.

  Specific examples of the acidic catalyst used for the synthesis of the novolak-type resorcin resin include acids such as oxalic acid, hydrochloric acid, sulfuric acid, diethyl sulfuric acid and p-toluenesulfonic acid. These may be used alone or in combination of two or more. In addition, since resorcin itself exhibits acidity, the synthesis reaction of the novolak-type resorcin resin may be carried out without using a catalyst.

  In the synthesis of the novolak-type resorcin resin, the reaction molar ratio of resorcins to aldehydes is preferably 0.40 to 0.80 moles of aldehyde per 1 mole of resorcin, more preferably resorcin The amount of aldehyde is at least 0.45 mol and at most 0.75 mol per 1 mol. The handling property of resin improves that the reaction molar ratio of resorcins and aldehydes is more than the said lower limit. It becomes easy to control the synthesis reaction of novolak-type resorcinol resin that the reaction molar ratio of resorcins and aldehydes is below the above-mentioned upper limit.

  The phenol resin composition for a friction material according to the present embodiment contains hexamethylenetetramine as a curing agent. This hexamethylenetetramine is an adduct in which an intermolecular adduct of the hexamethylenetetramine and the above-mentioned high ortho novolac phenol resin is formed from the viewpoint of improving the reactivity between the high ortho novolac phenol resin and the novolak resorcinol resin. That is, it is preferable to be contained in the form of an adduct compound in the phenol resin composition for a friction material according to the present embodiment.

  The proportion of those forming the adduct in the total amount of hexamethylenetetramine, that is, the adducting ratio is preferably 30% or more, and more preferably 32% or more. By making the adduct ratio of hexamethylenetetramine equal to or higher than the above numerical range, it is possible to reduce the intermolecular distance between the high ortho novolac phenol resin, the novolac resorcinol resin, and the hexamethylenetetramine. As a result, it is possible to improve the reactivity of hexamethylenetetramine with the high ortho novolac phenolic resin and the novolac resorcinol resin.

Here, adducted hexamethylenetetramine refers to hexamethylenetetramine which is not extracted by ion-exchanged water at 25 ± 1 ° C. In general, hexamethylenetetramine, which is merely ground and mixed in a phenolic resin, is easily extracted by water. On the other hand, adducted hexamethylenetetramine, that is, hexamethylenetetramine finely dispersed in a phenol resin is not extracted with water because each finely divided particle is contained in the phenol resin. Then, the adductation ratio of hexamethylenetetramine (proportion of adducted hexamethylenetetramine) can be obtained from the following equation. In the following formula, A refers to the mass of total hexamethylenetetramine determined by Kjeldahl method, liquid chromatography method or elemental analysis method, and B is hexamethylenetetramine extracted with ion-exchanged water determined by titration method Refers to the mass of In the measurement, the particle size of the sample is 150 μm or less, and if the particle size is coarse, the particle size of the sample is pulverized to 150 μm or less and then measured.
Adduct ratio = [(A-B) / A] x 100 (%)

  In the phenolic resin composition for a friction material according to the present embodiment, the content of hexamethylenetetramine is the total value of the content of the high ortho novolac type phenolic resin and the content of the novolac type resorcinol resin in the resin composition. When 100 parts by mass is used, the amount is preferably 5 parts by mass or more and 20 parts by mass or less, and more preferably 7 parts by mass or more and 18 parts by mass or less with respect to 100 parts by mass of the total value. By setting the content of hexamethylenetetramine to the above lower limit value or more, it is possible to obtain a minimum crosslink density. Further, by setting the content of hexamethylenetetramine to the above upper limit value or less, it is possible to reduce the amount of gas generation at the time of molding.

  In the phenolic resin composition for a friction material according to the present embodiment, the content of free phenol is preferably less than 1% by mass, and more preferably less than 0.9% by mass. By setting the content of free phenol to the upper limit value or less, volatilization of the phenol component can be suppressed, and a good working environment can be formed. The content of free phenol in the phenolic resin composition for friction material is reduced by performing processing such as removing the above free phenol under high vacuum conditions in the production stage of phenol resin which is one of the manufacturing raw materials. It can be done.

  The phenol resin composition for a friction material according to the present embodiment preferably has a maximum torque of 1 N · m or more and 20 N · m or less when cured at 150 ° C. By so doing, it is possible to realize a phenolic resin composition for friction material excellent in moldability. Furthermore, according to the phenolic resin composition for a friction material having a maximum torque within the above numerical range, the amount of gas generated from the inside can be reduced when molding the friction material using the resin composition, It is possible to suppress the occurrence of cracking and swelling in the produced friction material. In addition, the maximum torque of the phenol resin composition for friction materials can be measured, for example, by the following method using a torque measuring device. The viscosity increase of the resin composition accompanying the reaction of melting and curing the phenolic resin composition for friction material in a die set at 150 ° C. is detected by the current value acting on the motor. The maximum value of the current value detected in this manner is taken as the maximum torque value when cured at 150 ° C.

  In the phenolic resin composition for friction material according to the present embodiment, tartaric acid, oxalic acid, malonic acid, fumaric acid, benzoic acid, as long as the object of the present invention is not impaired, in addition to the components described above. And organic acids such as phthalic acid, random novolac type phenol resins, resol type phenol resins, resorcinol monomers, and the like. Among them, when an organic acid is contained, it is possible to improve the rapid curing property of the phenolic resin composition for friction material.

<Method of Producing Phenolic Resin Composition for Friction Material>
The phenolic resin composition for a friction material according to the present embodiment can be obtained, for example, by a method of melt-mixing a high ortho novolac type phenolic resin, a novolac type resorcinol resin, and hexamethylenetetramine. When this method is adopted, a resin mixture of high ortho novolac type phenol resin and novolac type resorcinol resin may be used. In addition, in the fluid state where the high ortho novolac type phenol resin, the novolak type resorcinol resin, and the hexamethylenetetramine melt respectively, the curing reaction by the hexamethylene tetramine of the high ortho novolac type phenol resin is substantially the same as the melt mixing described above. It refers to mixing without happening. As a specific melt mixing method, a method in which a predetermined amount of a high ortho novolac phenol resin, a novolak resorcinol resin, and hexamethylenetetramine are charged in a mixing apparatus and melt mixed is preferable. The melt mixing temperature is preferably a temperature at which the high ortho novolac phenol resin melts but the curing reaction does not start. Examples of the mixing device include pressure kneaders such as a pressure kneader, a twin screw extruder, and a single screw extruder.

  Here, when the high ortho novolak type phenol resin, the novolak type resorcinol resin, and hexamethylenetetramine are mixed in a general reaction container, disadvantages such as increase in resin viscosity and progress of gelation reaction occur. It is difficult to mix stably. However, in the case of using the above-mentioned pressurized type kneading apparatus, it is possible to make the dispersed state of hexamethylenetetramine in the high ortho novolac type phenol resin and the novolac type resorcinol resin favorable as well as hexamethylene. It is possible to adduct tetramine. Specifically, the proportion of the adduct in the total amount of hexamethylenetetramine, that is, the adduct ratio, by using a high-pressure novolak type phenolic resin, a novolac type resorcinol resin, and hexamethylenetetramine using a pressure-type kneader It is possible to prepare so as to be 30% or more.

<Friction material>
The friction material according to the present embodiment is obtained by mixing a fibrous base material, a filler, and a binder containing the above-described phenolic resin composition for friction material, and thermoforming the obtained mixture as a raw material composition. It is manufactured. By doing this, it is possible to obtain a friction material excellent in heat resistance without reducing various properties.

  Specific examples of the fiber base material to be contained in the friction material according to this embodiment include steel fibers, copper fibers, glass fibers, ceramic fibers, inorganic fibers such as potassium titanate fibers, and organic fibers such as aramid fibers. These may be used alone or in combination of two or more. Among them, it is preferable to include organic fibers such as aramid fibers.

  Specific examples of the filler to be contained in the friction material according to the present embodiment include calcium carbonate, calcium hydroxide, barium sulfate, mica, inorganic fillers such as abrasive, kallion and talc, organic fillers such as cashew dust and rubber dust And lubricants such as graphite, antimony trisulfide, molybdenum disulfide and zinc disulfide. These may be used alone or in combination of two or more. Among them, it is preferable to use an inorganic filler.

  The friction material according to the present embodiment can be produced, for example, by the following method. However, the method of manufacturing the friction material according to the present embodiment is not limited to the following example.

  First, a powdery raw material including a fiber base and a filler, and a binder are weighed so as to have a predetermined composition ratio, and these are mixed using a mixer. In addition, general things, such as an Eirich mixer etc., are mentioned as a specific example of a mixer. Next, a predetermined amount of the raw material composition obtained by mixing is divided and preformed to form a block body. Thereafter, the obtained preformed body is put into a mold heated to, for example, 150 ° C., and pressed for about 3 to 7 minutes to produce a molded body. Then, the produced molded body is heat treated at, for example, a temperature of 200 ° C. or more for about 1 hour to be cured, whereby the friction material according to the present embodiment can be obtained.

  Here, the friction material according to the present embodiment is used to form a friction component such as a brake.

Note that the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like as long as the object of the present invention can be achieved are included in the present invention.
Hereinafter, examples of the embodiment will be additionally described.
1. High ortho novolac type phenolic resin,
Novolak-type resorcinol resin,
With hexamethylenetetramine,
And a phenolic resin composition for friction material containing the same.
2. The phenolic resin composition for a friction material comprises an adduct of the hexamethylenetetramine and the high ortho novolac phenolic resin. The phenolic resin composition for friction materials as described in 4.
3. The amount of hexamethylenetetramine forming the adduct is 30% or more with respect to the total amount of hexamethylenetetramine contained in the phenolic resin composition for a friction material. The phenolic resin composition for friction materials as described in 4.
4. The content of the novolac-type resorcinol resin is 1 part by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the high ortho novolac-type phenol resin. To 3. The phenolic resin composition for friction materials as described in any of the above.
5. The ortho / para bond ratio of the high ortho novolac type phenolic resin is 1 or more and 9 or less. To 4. The phenolic resin composition for friction materials as described in any of the above.
6. The weight average molecular weight of the high ortho novolac phenolic resin is 1,000 or more and 8,000 or less. To 5. The phenolic resin composition for friction materials as described in any of the above.
7. The content of free phenol is less than 1% by mass with respect to the total amount of the high ortho novolac phenol resin. To 6. The phenolic resin composition for friction materials as described in any of the above.
8. When the total value of the content of the high ortho novolac phenol resin and the content of the novolac resorcinol resin is 100 parts by mass,
The content of the hexamethylenetetramine is 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass in total of the content of the high ortho novolac phenol resin and the content of the novolac resorcinol resin. 1. To 7. The phenolic resin composition for friction materials as described in any of the above.
9. Obtained by melt-mixing the high ortho novolac phenolic resin, the novolac resorcinol resin, and the hexamethylenetetramine; To 8. The phenolic resin composition for friction materials as described in any of the above.
10. 8. obtained by melt-mixing a resin mixture of the high ortho novolac phenol resin and the novolac resorcinol resin with the hexamethylenetetramine; The phenolic resin composition for friction materials as described in 4.
11. A fiber substrate,
With fillers
A binder,
A friction material containing
The binder is To 10. A friction material comprising the phenolic resin composition for a friction material according to any one of the above.
12. The fiber substrate comprises an organic fiber, 11. The friction material described in.
13. The filler comprises an inorganic filler; Or 12. The friction material described in.
14. 11. To 13. A brake formed using the friction material according to any one of the above.

  Hereinafter, the present invention will be described by way of Examples and Comparative Examples, but the present invention is not limited thereto. Moreover, all "parts" shown by an Example and a comparative example represent "mass part", and all "%" represents "mass%." The weight average molecular weight (Mw) of the high ortho novolac phenol resin obtained by the synthesis of the high ortho novolac phenol resin is measured by gel permeation chromatography (GPC) of the tetrahydrofuran (THF) soluble fraction, and polystyrene Calculated by conversion.

The measurement conditions of GPC are shown below.
Device: HLC-8320 (made by Tosoh Corporation)
Detector: RI

Column: 1 station of TSK-GEL G1000H (made by Tosoh Corp.) and 2 stations of TSK-GEL G2000H (made by Tosoh Corp.) were used in series connected in this order.
Temperature: 40 ° C
Solvent: THF
Flow rate: 1.0 ml / min Sample: 50 μl injection of 1 wt% concentration sample

  Further, the free phenol content of the high ortho novolac type phenolic resin obtained by the synthesis of the high ortho novolac type phenolic resin can be reduced by using the obtained phenolic resin as a gas chromatograph "GC-2014" manufactured by Shimadzu Corporation, Agilent Technologies, Inc. The measurement was performed using a column "DB-WAX" manufactured and calculated.

Furthermore, the ortho / para bond ratio of the high ortho novolac phenol resin obtained by the synthesis of the high ortho novolac phenol resin was measured by infrared absorption spectroscopy. FT-IR device used (Nicolet Co. · Avatar320), when carried out by a KBr method, the wave number 760 cm ^-1, and, from the absorbance of wave numbers 820 cm ^-1, was calculated ortho / para bond ratio by the following equation. D760 in the following formula indicates the absorbance at 760 cm ^-1, D820 shows the absorbance of the 820 cm ^-1.
Formula: ortho / para coupling ratio = D760 / (1.44 × D820)

(Synthesis of high ortho novolac phenolic resin)
(Resin synthesis example 1)
A mixture of 1000 parts of phenol, 600 parts of 37% formalin and 2 parts of zinc acetate is reacted at 100 ° C. for 3 hours, then dehydrated by atmospheric distillation until the temperature of the reaction mixture reaches 140 ° C., and further to 0.9 kPa While gradually reducing the pressure, the reaction mixture was dehydrated by distillation under reduced pressure until the temperature of the reaction mixture reached 180 ° C. to remove monomers, thereby obtaining 1000 parts of a high ortho novolac type phenolic resin A. The weight average molecular weight of the high ortho novolac phenol resin A was 6000, and the free phenol was 0.6%. Further, the ortho / para bond ratio of the high ortho novolac type phenol resin A was 5.7, and the F / P was 0.70.

(Resin synthesis example 2)
A mixture of 1000 parts of phenol, 550 parts of 37% formalin and 2 parts of zinc acetate is reacted at 100 ° C. for 2 hours and 30 minutes, dehydrated by atmospheric distillation until the temperature of the reaction mixture reaches 140 ° C., and further 0.9 kPa The reaction mixture was dewatered by distillation under reduced pressure until the temperature of the reaction mixture reached 180 ° C. while gradually reducing the pressure until demonomerization to obtain 950 parts of a high ortho novolac type phenolic resin B. The weight average molecular weight of the high ortho novolac type phenol resin B was 4000, and the free phenol was 0.7%. In addition, the ortho / para bonding ratio of the high ortho novolac phenol resin B was 4.1, and the F / P was 0.64.

(Resin synthesis example 3)
A mixture of 1000 parts of phenol, 500 parts of 37% formalin and 2 parts of zinc acetate is reacted at 95 ° C. for 3 hours, dehydrated by atmospheric distillation until the temperature of the reaction mixture reaches 140 ° C., and further to 0.9 kPa While gradually reducing the pressure, the reaction mixture was dewatered by distillation under reduced pressure until the temperature of the reaction mixture reached 180 ° C. to demonomer, to obtain 900 parts of a high ortho novolac type phenolic resin C. The weight average molecular weight of the high ortho novolac phenol resin C was 2000, and the free phenol was 0.7%. In addition, the ortho / para bonding ratio of the high ortho novolac phenol resin C was 2.5, and the F / P was 0.58.

(Synthesis of novolac type phenolic resin)
A mixture of 1000 parts of phenol, 570 parts of 37% formalin and 10 parts of oxalic acid is reacted at 100 ° C. for 3 hours, dehydrated by atmospheric distillation until the temperature of the reaction mixture reaches 140 ° C., and further to 0.9 kPa While gradually reducing the pressure, the reaction mixture was dehydrated by distillation under reduced pressure until the temperature of the reaction mixture reached 200 ° C. to demonomerize, to obtain 910 parts of novolac-type phenolic resin D. The weight average molecular weight of the novolac phenol resin D was 9000, and the free phenol was 0.3%. Further, the ortho / para bonding ratio of novolac type phenol resin D was 0.8, and F / P was 0.66.

(Synthesis of novolak-type resorcinol resin)
A mixture of 1000 parts of resorcin and 3 parts of oxalic acid was heated to 100 ° C., and 400 parts of 37% formalin was added sequentially over 30 minutes. Then, it is reacted for 1 hour, dehydrated by atmospheric distillation until the temperature of the reaction mixture reaches 140 ° C., and further reduced pressure distillation until the temperature of the reaction mixture reaches 180 ° C. while gradually reducing the pressure to 0.9 kPa. The reaction mixture was dehydrated and demonomerized to obtain 910 parts of novolak resorcin resin E.

(Examples 1-1 to 1-6, comparative examples 1-1 to 1-5)
While producing a phenol resin composition by the following method, evaluation was performed by the evaluation method mentioned later. The results are summarized in Table 1 below.

(Preparation of Phenolic Resin Composition)
Example 1-1
800 parts of high ortho novolac type phenol resin A, 200 parts of novolak type resorcinol resin E, 120 parts of hexamethylenetetramine, equal ratio of supply per unit time, to a twin-screw extruder controlled at an inlet temperature of 80 ° C and an outlet temperature of 90 ° C It supplied so that it might become, and the kneaded material which came out from the exit was cooled, and solid phenol resin composition A (adductation rate 40% of hexamethylenetetramine, free phenol content 0.5%) was obtained at normal temperature.

Example 1-2
In a pressure kneader, 900 parts of high ortho novolac type phenol resin B, 100 parts of novolac type resorcinol resin E and 130 parts of hexamethylenetetramine were charged, and the temperature was raised to 90 ° C. to melt for 10 minutes. A phenolic resin composition B (adductation ratio of hexamethylenetetramine 69%, free phenol content 0.6%) which is solid at normal temperature was obtained.

Example 1-3
Into a twin-screw extruder controlled at an inlet temperature of 85 ° C and an outlet temperature of 95 ° C, 950 parts of high ortho novolac type phenol resin C, 50 parts of novolac type resorcinol resin E, 150 parts of hexamethylenetetramine, the supply ratio per unit time is equal The kneaded product coming out of the outlet was cooled to obtain a phenolic resin composition C (adductation ratio of hexamethylenetetramine 56%, free phenol content 0.6%) which is solid at normal temperature.

Example 1-4
In a pressure kneader, 400 parts of high ortho novolac type phenol resin A, 600 parts of novolak type resorcinol resin E and 100 parts of hexamethylenetetramine were charged, heated to 90 ° C., and melted for 10 minutes. A phenolic resin composition D (adductation ratio of hexamethylenetetramine 32%, free phenol content 0.2%) which is solid at normal temperature was obtained.

Example 1-5
950 parts of high ortho novolac type phenol resin B, 50 parts of novolac type resorcinol resin E, 120 parts of hexamethylene tetramine are charged in a grinder, and mixed by pulverization to obtain a powder phenol resin composition E (adductation ratio of hexamethylene tetramine 0%, free phenol The content was 0.6%).

Example 1-6
500 parts of high ortho novolac type phenol resin A, 500 parts of novolak type resorcinol resin E, 140 parts of hexamethylenetetramine, the supply ratio per unit time is equal to a twin-screw extruder controlled at an inlet temperature of 85 ° C and an outlet temperature of 95 ° C. The kneaded product coming out of the outlet was cooled to obtain a phenolic resin composition F (the adduct ratio of hexamethylenetetramine 43%, free phenol content 0.3%) in a form at normal temperature.

Comparative Example 1-1
To a twin screw extruder controlled at an inlet temperature of 80 ° C. and an outlet temperature of 90 ° C., 1000 parts of high ortho novolac phenol resin A and 130 parts of hexamethylenetetramine are supplied so that the feed ratio per unit time becomes equal, The kneaded material which came out was cooled, and the phenol resin composition G (adductation ratio of hexamethylenetetramine 45%, free phenol content 0.5%) of the form at normal temperature was obtained.

Comparative Example 1-2
1000 parts of high ortho novolac type phenol resin C and 150 parts of hexamethylenetetramine are charged in a grinder and pulverized and mixed to obtain powder phenol resin composition H (hexamethylene tetramine adduct ratio 0%, free phenol content 0.6%) Obtained.

Comparative Example 1-3
1000 parts of novolac type phenol resin D and 150 parts of hexamethylenetetramine are charged in a grinder and pulverized and mixed to obtain powdery phenol resin composition I (0% adduct of hexamethylenetetramine, content of free phenol 0.3%) The

Comparative Example 1-4
In a pressure kneader, 800 parts of novolak-type phenol resin D, 200 parts of novolak-type resorcin resin E, and 120 parts of hexamethylenetetramine were charged, heated to 90 ° C., and melted for 10 minutes. A phenolic resin composition J (adductation ratio of hexamethylenetetramine 38%, free phenol content 0.2%) which is solid at normal temperature was obtained.

<Comparative Example 1-5>
In a pressure kneader, 1000 parts of novolak-type resorcin resin E and 150 parts of hexamethylenetetramine were charged, the temperature was raised to 90 ° C., and melting was performed for 10 minutes. A phenolic resin composition K (adductation ratio of hexamethylenetetramine 40%, free phenol content 0%) which is solid at normal temperature was obtained.

(Evaluation method of phenol resin composition)
(1) Proportion of adduct in total amount of hexamethylenetetramine (adductation rate of hexamethylenetetramine)
The adductation rate of hexamethylenetetramine was determined from the following equation. In the following formula, A refers to the mass of all hexamethylenetetramines determined by the Kjeldahl method, and B refers to the mass of hexamethylenetetramines extracted by ion exchange water determined by the titration method. Moreover, in the case of a measurement, the particle size of the sample used what was adjusted to 150 micrometers or less.
Adduct ratio = [(A-B) / A] x 100 (%)

(2) Free phenol content The obtained phenol resin composition is measured using a gas chromatograph "GC-2014" manufactured by Shimadzu Corporation, a column "DB-WAX" manufactured by Agilent Technologies, Inc., and contains free phenol. The amount was calculated.

(Examples 2-1 to 2-6, comparative examples 2-1 to 2-5)
While preparing the mixture for friction material by the following method, evaluation was performed by the evaluation method mentioned later. The results are summarized in Table 2.

(Preparation of a mixture for friction material)
Friction material phenolic resin compositions A to K obtained in Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-5 as binders and aramid fibers (Kevlar manufactured by DU PONT Co., Ltd.) as fiber base materials Using calcium carbonate (manufactured by Sankyo Seimitsu Co., Ltd., calcium carbonate) and barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd., fertile barium sulfate) as inorganic fillers, respectively, at a blending ratio shown in Table 2 It mixed and was set as the mixture for friction materials.

(Evaluation method of mixture for friction material)
(1) Minimum moldable time (curability at molding stage)
Using a thermoforming press, the mixture for the friction material obtained by charging and mixing at the above mixing ratio is molded at 180 ° C. under a pressure of 30 MPa for a molding time of 10 seconds from 60 seconds to 180 seconds, and removed The minimum time for obtaining a molded product of 90 mm long × 60 mm wide × 13 mm thickness without forming blisters or cracks at the time of molding or demolding was taken as the shortest possible molding time. It is judged that the curability at the time of molding is better as the shortest moldable time is shorter.

(2) Glass transition temperature Tg (curability at the baking stage)
Using a thermoforming press, the mixture for a friction material obtained by charging and mixing at the above mixing ratio was molded at 180 ° C. under a pressure of 30 MPa for 3 minutes to obtain a test piece for glass transition temperature measurement. The obtained test piece is as it is (before the baking treatment), and after being placed in a dryer adjusted to 250 ° C. for 10 minutes for baking treatment, the glass transition temperature in the bending mode of dynamic viscoelasticity measurement (DMA) The Tg was measured. The glass transition temperature Tg was determined by extrapolating the temperature at which the storage modulus decreased. Even with a short baking time, the crosslink density (degree of curing) increases, and the higher the glass transition temperature Tg, the better it is judged.

(3) Bending strength A mixture for friction material obtained by preparing and mixing at the above mixing ratio using a thermoforming press machine for 7 minutes at 170 ° C. and a pressure of 20 MPa, then baking at 200 ° C. for 60 minutes and bending test I got a piece. The obtained bending test piece was measured in accordance with JIS K 7171 "Plastic-Determination of bending characteristics". After the baking, those measured at normal temperature (25 ° C.) are normal strength, and after baking, they are heat treated at 350 ° C. for 4 hours and then measured at normal temperature (25 ° C.) as heat treated strength. It is judged that the higher the bending strength after the heat treatment, the less the thermal degradation and the better the heat resistance.

(4) Rockwell Hardness The bending test piece obtained by the above-mentioned method was measured at normal temperature (25 ° C.) after baking according to JIS K 7202 “Testing method for Rockwell hardness of plastic”. The higher the Rockwell hardness, the better the degree of crosslinking and the better the mechanical properties.

(5) High temperature short time molding evaluation The mixture for a friction material obtained by preparing and mixing at the above mixing ratio using a thermoforming press machine is molded at 180 ° C. under a pressure of 30 MPa for 2 minutes, 90 mm × 60 mm × thickness A molded product of 13 mm in diameter was obtained, and it was confirmed whether blistering or cracking occurred. Those with neither blistering nor cracking were described as ◎, those with blistering or cracking noted as Δ, and those with both blistering and cracking as ×.

  Next, baking was performed at 250 ° C. for 20 minutes while the temperature of the molded product did not fall below 100 ° C., and then it was confirmed whether blistering or cracking occurred. Those that did not generate blisters or cracks were marked as ◎, and those that had slight blisters or cracks were marked as ○. The baking process was not performed about what the defect generate | occur | produced after shaping | molding.

  As shown in Table 2, with regard to the curability at the molding stage, Examples 2-1 to 2 are a mixture for a friction material using the phenol resin composition for a friction material of Examples 1-1 to 1-6. The molded product of the mixture for friction material of No.-6 is Comparative Example 1-1 in which novolak-type resorcinol resin was not used, and Comparative Example 1-2 in which novolac-type resorcinol resin was not used and adducting was not performed, High Phenolic resin composition for a friction material of Comparative Example 1-3 in which the ortho novolac type phenolic resin and the novolac type resorcinol resin were not used, and Comparative Example 1-4 in which the novolac type phenolic resin was used instead of the high ortho novolac type phenolic resin Compared with Comparative Examples 2-1 to 2-4, which are molded articles of a mixture for friction material using the above, it can be seen that the shortest moldable time is short and the curability at the molding stage is excellent. It was. Further, Comparative Example 2-5, which is a molded article of a mixture for a friction material using the phenolic resin composition for a friction material of Comparative Example 1-5 using only the novolak type resorcinol resin without using the high ortho novolac type phenolic resin Could not be molded.

  Further, as shown in Table 2, with respect to the curability in the baking step, the molded product of the mixture for friction material of Examples 2-1 to 2-6 is the mixture for friction material of Comparative Examples 2-1 to 2-4. It was found that the glass transition temperature after molding (before the baking treatment) was close to the molding temperature, and the glass transition temperature after the baking treatment was also close to the baking temperature, as compared with the molded articles of the above.

  In addition, as shown in Table 2, after heat treatment at 350 ° C. for 4 hours, the bending strength (strength after heat treatment) measured at normal temperature (25 ° C.) When compared with the molded product of the mixture for friction material of Comparative Example 2-1 and Comparative Example 2-2, it was found that the molded product has high strength after heat treatment and exhibits excellent heat resistance.

  Further, as shown in Table 2, with respect to Rockwell hardness, the molded product of the mixture for friction material of Examples 2-1 to 2-6 is the mixture of friction material for Comparative Example 2-1 and Comparative Example 2-2. It was found that the hardness was high and the crosslinking degree was excellent as compared to the molded product.

  Furthermore, as shown in Table 2, with respect to the appearance after molding for a short time at high temperature, the molded article of the mixture for friction material of Examples 2-1 to 2-6 is the friction material of Comparative Examples 2-1 to 2-4. It was found that the appearance after molding at high temperature for a short time was excellent as compared with the molded product of the mixture. Furthermore, in the moldings of the friction material mixture of Examples 2-1 to 2-3 and 2-6, no blisters or cracks occurred even after the baking treatment at 250 ° C. for 20 minutes, Good results were obtained.

  From the above results, the mixture for a friction material using the phenolic resin composition for a friction material of the present invention can shorten the curing time. Moreover, the molded article containing the mixture for friction materials using the phenol resin composition for friction materials of this invention had high hardness, and showed the outstanding heat resistance. Further, it was found that the mixture for a friction material using the phenolic resin composition for a friction material of the present invention is applicable to high temperature short time molding after forming for a short time at high temperature without causing cracking or swelling. . Therefore, according to the present invention, it is possible to obtain a phenol resin composition for friction material which can obtain a friction material excellent in heat resistance at low cost without deteriorating various properties such as mechanical properties. Further, according to the present invention, it is possible to obtain a phenol resin composition for friction material that is applicable to high temperature short time molding.

  The phenolic resin composition for a friction material according to the present invention achieves a high degree of cure even if the curing time is shortened, thereby achieving a low cost and high heat resistance friction material without deteriorating various properties such as mechanical properties. For example, it can be used suitably for manufacture of industrial friction materials, such as a brake.

  This application claims priority based on Japanese Patent Application No. 2014-022070 filed Feb. 7, 2014, the entire disclosure of which is incorporated herein.

Claims (13)

High ortho novolac type phenolic resin,
Novolak-type resorcinol resin obtained by the reaction of resorcinol with formaldehyde ;
With hexamethylenetetramine,
Only including,
The ortho / para bond ratio of the high ortho novolac type phenolic resin is 2 or more and 7 or less,
Phenolic resin composition for friction material.   The phenolic resin composition for friction materials according to claim 1, wherein the phenolic resin composition for friction materials comprises an adduct of the hexamethylenetetramine and the high ortho novolac type phenolic resin.   The friction material according to claim 2, wherein the amount of the hexamethylenetetramine forming the adduct body is 30% or more with respect to the total amount of the hexamethylenetetramine contained in the phenolic resin composition for a friction material. Phenolic resin composition.   The friction material according to any one of claims 1 to 3, wherein a content of the novolac resorcin resin is 1 part by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the high ortho novolac phenol resin. Phenolic resin composition. The high weight average molecular weight of ortho novolak type phenolic resin, friction material phenolic resin composition according to any one of claims 1 to 4 1,000 or more than 8,000. The phenolic resin composition for a friction material according to any one of claims 1 to 5 , wherein the content of free phenol is less than 1% by mass with respect to the total amount of the high ortho novolac type phenolic resin. When the total value of the content of the high ortho novolac phenol resin and the content of the novolac resorcinol resin is 100 parts by mass,
The content of the hexamethylenetetramine is 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass in total of the content of the high ortho novolac phenol resin and the content of the novolac resorcinol resin. The phenol resin composition for friction materials as described in any one of Claims 1 thru | or 6 . The phenol resin composition for a friction material according to any one of claims 1 to 7 , which is obtained by melt-mixing the high ortho novolac phenol resin, the novolak resorcinol resin, and the hexamethylenetetramine. The phenolic resin composition for a friction material according to claim 8 , obtained by melt-mixing a resin mixture of the high ortho novolac type phenolic resin and the novolac type resorcinol resin with the hexamethylenetetramine. A fiber substrate,
With fillers
A binder,
A friction material containing
A friction material, wherein the binder comprises the phenolic resin composition for a friction material according to any one of claims 1 to 9 . 11. The friction material of claim 10 , wherein the fibrous substrate comprises organic fibers. It said filler comprises an inorganic filler, a friction material according to claim 10 or 11. A brake formed using the friction material according to any one of claims 10 to 12 .